Promotion Quest Rewards Issue

My character is level 25 Swashbuckler, and just leveled Dead Mike up to level 21. I got his promotion quest, 'The Water of Life' for his second tier, Revenant, I believe. On the quest rewards on the bottom, it labels his new tier AND it says it rewards me 1 experience. I have had this bug once before with Bonnie Anne, for her Sniper Promotion. I was playing solo at both times. Is this a bug, or is it just some kinda trick to make us go crazy?